He told his wife he'd gone fishing. But when a photograph of Dick Cheney, the US vice-president, appeared on the White House website, the smile on his face and the reflection in his sunglasses left some questioning his catch.

The reflection appears to show the double image of a naked woman cavorting during a fly-fishing trip along Idaho's Snake River. Cheney's staff, however, insist his renowned love of outdoor sports does not extend to entertaining young ladies, with or without their clothes, on his fishing expeditions.

"Clearly the picture shows a hand casting a rod," said Meagan Mitchell, the vice-president's press secretary. But since the photograph was published, the internet has been awash with speculation.

Almost 60% of respondents to a straw poll on AOL's Political Machine blog voted for "hot babe sunbathing" as the likely answer. Other options included that the picture wasn't of Cheney, that it had been digitally altered, or even that it showed an "alien overlord". Others suggested that the image is of a man smoking a cigar.

One Australian website likened the photograph to a Playboy cartoon from the 1970s; "the rugged outdoorsman smiling as the reflection of a naked woman appears in the lenses of his aviator sunglasses".

Photography experts, however, say that it is all a fishy tale. Geoff Bridges, a senior photo editor with McClatchy-Tribune Newspapers, concluded after a high-resolution digital analysis that the reflection in the sunglasses was, after all, Cheney's hand on his fishing rod.

"In one lens you can clearly tell it is the sleeved arm of Cheney or a fishing companion," he said.

"The other lens has an extreme distortion that, without looking at it closely, could be misconstrued."